package net;

import java.io.IOException;
import java.net.*;
import java.util.Scanner;

public class UdpEchoClient {
    private DatagramSocket socket = null;
    private String serverIP;
    private int serverPort;
    public UdpEchoClient(String serverIP ,int serverPort) throws SocketException {
        socket =new DatagramSocket();
        this.serverIP=serverIP;
        this.serverPort =serverPort;
    }

    public void start() throws IOException {
        System.out.println("启动客户端!");
        Scanner scanner= new Scanner(System.in);

        while(true){
            //1.从控制台读取用户的输入
            System.out.print("-> ");
            String request = scanner.next();
            //2.构造出一个UDP请求,发送给服务器
            DatagramPacket requestPacket= new DatagramPacket(request.getBytes(),request.getBytes().length,
                    InetAddress.getByName(this.serverIP),this.serverPort);//这里要将IP字符串转换成int类型
            socket.send(requestPacket);
            //3.从服务器中读取响应
            DatagramPacket responsePacket= new DatagramPacket(new byte[4096],4096);
            socket.receive(responsePacket);
            String response= new String(responsePacket.getData(),0,requestPacket.getLength());
            //4.把响应打印到控制台上
            System.out.println(response);
        }
    }

    public static void main(String[] args) throws IOException {
        //127.0.0.1称为环回IP,代表本机,如果服务器和客户端在同一个主机上,就使用这个IP
        UdpEchoClient udpEchoClient =new UdpEchoClient("127.0.0.1",9090);
        udpEchoClient.start();
    }
}
